Get ready for Friday’s flyby of the 150-long rocky asteroid 2012 DA14. Credit: NASA/JPL-Caltech
Near-Earth asteroid 2012 DA14 has become a sizzling topic online and on the TV news. Not a week goes by lately when I don’t hear about “the asteroid that’s going to fly by Earth”. Yesterday John, my mailman, asked me about it.
“Supposed to be half as long as a football field,” he offered. John was right. It’s a good-sized rock – the largest we know of to approach Earth this closely.
It’s fun that folks are excited about this 150-foot long solar system vagabond. I only wish we’d all have a chance to see it. Using the charts and tips below, it’s my hope that many of you will.
2012 DA14 was discovered by astronomers in the La Sagra Sky Survey program in Spain in February 2012. With an orbital period (time it takes to go around the sun) of about 368 days it makes annual spins by Earth. Friday’s flyby will be the closest the asteroid has been for many years and the closest it will come for at least the next 30.
And we do mean close. On Feb. 15 at about 1:24 p.m. (CST), 2012 DA14 will zoom 17,200 miles above the Earth’s surface traveling at 17,400 mph. While this is a record approach for a known object of this size, other smaller asteroids have skimmed nearer yet.
We only have to look back to June 27, 2011 when 2011 MD, about 20-50 feet wide, passed just 7,500 miles overhead. No harm came to Earth’s nail-biting residents then and none will during Friday’s pass. The record by the way for the closest-known shave goes to the petite, 3-foot-long 2011 CQ1 at 3,400 miles on Feb. 4, 2011.
2012 DA14 will briefly fly between the geostationary belt of communications satellites (white dots) and the Earth during closest approach Friday Feb. 15. Notice how it comes from under the Earth, moving from south to north. Credit: Simone Corbellini
On average, we’d expect an object of 2012 DA 14’s size to get this close to the Earth about once every 40 years. An actual collision by something this big is far rarer – about once every 1200 years.
On its inbound leg, 2012 DA14 will buzz between the constellation of GPS satellites, which orbit at about 12,600 miles, and the ring of geostationary satellites located about 22,200 miles above Earth’s equator. None will be in danger because the asteroid will come up from below and pass through the empty zone between the two.
Some 300 active weather and communications satellites are parked in orbit in the ring and relay communications around the globe. When your favorite TV weatherperson flashes pictures of storms and hurricanes taken from space, you can bet it was photographed and transmitted back to Earth by a geostationary satellite. There are presently about 32 GPS satellites used by government and consumers alike to pinpoint precise locations on the ground.
Simulation of the original constellation of 24 GPS satellites orbiting Earth. Credit: Wikipedia
As the asteroid zips by, Earth’s gravity will bend its orbit, changing its orbital period from 368 to 317 days and making close approaches like this one less likely. As for 2012 DA14 striking any satellite at all, Donald Yeomans, head of NASA’s Near Earth Object Program Office at the Jet Propulsion Laboratory, says it’s “extremely remote.” Given the huge volume of space the asteroid must pass through as it swings by Earth and the tiny number of potential targets, we might liken it to a gnat in a mansion.
Despite its proximity, 2012 DA14’s tiny size means not even the largest telescopes will show it as more than a star-like point of light. If you live in eastern Europe, Asia or Australia, you’ll see the asteroid at its closest, when it not only be brightest but moving fastest. I’ve seen a few Earth-approaching asteroids, and they really can book across the sky, but few travel as fast as this one will. In just three hours centered on closest approach, 2012 DA14 will zip from the Southern Cross all the way to the Bowl of the Big Dipper!
World map with time zones. The area inside the red circle shows very approximately where the asteroid will be visible in a dark sky when it’s closest and brightest. Map credit: Wikipedia
It reaches peak brightness around 1:24 p.m. (CST) or 7:30 p.m. in London, England. While the sky will be dark there at that time, the asteroid will still not have risen in the east. We have to go travel farther east and south to catch it at its brightest. Let’s pick Athens, Greece. There the the sky will be dark early enough to spot the asteroid at its brightest (magnitude 7.4) low in Virgo around 10 p.m. local time using standard 40-50mm binoculars. Observers should look for a dim “star” slowly moving from south to north in the field of view.
A map from Heavens Above showing the entire sky from Jakarta, Indonesia. The labeled arc is the asteroid’s path during the night. Credit: Chris Peat
As we continue moving east across the globe, 2012 DA14 gets higher and higher in a dark sky. If you sense the eastern hemisphere has the best seats in the house, you’re right.
Residents of Jakarta, Indonesia for example will see the whole show from beginning to end. Fortunate sky watchers there can spot 2012 DA14 with a telescope around 1 a.m. Saturday morning Feb. 16 (local time) near the Southern Cross.
By 3 a.m. they can switch over to binoculars to catch it at maximum brightness. At dawn, the asteroid will have made a complete south-to-north beeline from Cross to Dipper and once again require a telescope to see. What a way to spend a night out, eh?
Did I say it was moving quickly? When nearest Earth, 2012 DA14 will hurry along at 1 degree or two full moon diameters per minute. Not only will you need binoculars, you’ll also need to know exactly where to look. By the time the sky is dark across the U.S., South America and Canada Friday night, the asteroid will have slowed considerably and faded to around magnitude 11.5 -12.
Sadly, U.S. sky watchers will need a 6-inch or larger telescope to find and follow it. The good news is that the asteroid will be conveniently placed in the northern sky near the Little Dipper.
The asteroid is shown at three times for an observer in Athens, Greece Friday evening facing east around 9:45 p.m. local time. 1 = 9:45 p.m., 2 = 10 p.m. and 3 = 10:15 p.m. Stars are plotted to about magnitude 7.5, the asteroid’s brightness at the time. Credit: Chris Marriott’s SkyMap software
I’ve given much thought on how to prepare charts for viewing 2012 DA14. When brightest, it’s not only crossing a great deal of sky in a hurry, but it’s so close to Earth that viewers in say, Vienna, will see it in a somewhat different part of the sky than those in Greece. You can’t make a one-size-fits-all chart for this bugger.
What I did instead was to create two charts – one for Athens, Greece and another for the central U.S. The Greek chart shows the asteroid when closest and brightest; the U.S. chart is centered on Duluth but is useful for a larger region, because the asteroid will be far enough away at that time for the path shift to be much smaller.
Just remember that you’ll need a telescope and good knowledge of the sky to find and follow our friend from the U.S. Use the charts to locate where the asteroid will be at a particular time and then wait for it to arrive as you gaze through the eyepiece.
2012DA14 will have faded to 11.5-12.0 magnitude when it gets dark enough to see it in the U.S., so you’ll need this more detailed chart to find it. Times are Central Standard for Friday Feb. 15, 2013. North is up and stars plotted to mag. 13. Brighter stars labeled with magnitudes. Right-click, save and print out for use at the telescope. Credit: Created with Emil Bonnano’s MegaStar atlas.
I highly recommend two websites that will show you a map of 2012 DA14’s path in your local sky as well as two other options for creating your own map:
* Heavens Above – Webmaster Chris Peat has prepared a special 2012 DA14 page on this well-known satellite prediction site. Head over, log in with your location and then click the 2012 DA14 link at the top of the page for a map with times. If you select a spot on the asteroid’s path and click again, you’ll be shown a detailed map with stars to 8th magnitude European, Asian and Down Under sky watchers will find these maps most useful.
* Visual SAT-Flare Tracker 3D - Select your location and click on the 2012 DA14 asteroid header. Then click on the “Best opportunity to see the asteroid from your location” link to see a star map and asteroid path. Be aware that the faintest stars shown here are only about 6th magnitude (naked eye limit), but they’ll still be quite useful for tracking; webmaster Simone Corbellini uses the very accurate JPL Horizons data (see below) for path-making.
* Do-it-yourself – If you have your own star-charting program that allows you to add new asteroids to the database, go to the Minor Planet Center and grab 2012 DA14’s orbital elements. Enter these into your program and print your own star chart. Again, because of how close the asteroid will be, its path might be somewhat different than what your program will show, but at least you’ll be in the neighborhood.
* Tedious but foolproof method – Head over to the JPL Horizon site, type 2012 DA14 into the search box, select your city, time interval (whether you want an asteroid position every 15 minutes, hour or whatever) and then click “Generate ephemeris”. You can hand-plot the positions listed onto a star chart you’ve made with your software program. Be aware that all the times are Universal Time or Greenwich Mean Time (GMT). Subtract 5 hours for Eastern time, 6 for Central and so on. This method has worked very well for me during previous close flybys.
Good luck and I hope a few of you get to see this running rock!